Here!! Here!!. We should have been more persistent in the 1960 when the USA
tried to move to the metric system.
*Clyde K. Spencer*
On Sat, Jan 30, 2021 at 5:34 PM David Eckhardt <davearea51a@...>
wrote:
Personally, I'm more at home in metric than our "kings foot" set of units!
However, if I had used metric, all the hams over here in the good 'ol USofA
would bellyache they couldn't deal with 2.54 cm/inch (conversion is on most
calculators) or, heaven forbid, Kelvins instead of degrees F. When
presenting, I warn the audience up-front that miles per hour has no place
in Fields and Waves in specifying c, only 3E8 m/sec and other metric units
shall be used.
Dave - W?LEV
(Born a Nerd, Always a Nerd........)
On Sat, Jan 30, 2021 at 7:24 PM Jean-Denis Muys via groups.io <jdmuys=
[email protected]> wrote:
Very interesting. I was quite shocked that you didn¡¯t use metric units
for
the calculations though. This would be my suggestion: use metric units.
JD
On Jan 30, 2021, at 07:23, Barry Feierman <k3euibarry@...>
wrote:
?Hello NANO VNA folks
I keep updating my NANO VNA talk after presenting at different club
meetings. I've had my Nano VNA for about four months now, and each time I
play with it I learn something new.
Questions raised by viewers made me reconsider how to explain PHASE and
RESONANCE and especially what the SMITH CHART reveals.
It feels like PHASE is greatly misunderstood, with antennas.
I tried to come up with a simple mechanical analogy: GRAMPY pushing
GRANDCHILD on a swing.
Even little grandkids know that GRAMPY has to push the swing at just
the
right time (PHASE) to increase the amplitude of the kid's swinging.
We all "know" that. If Grampy does not push at the right time, the
grandkid complains.
Do antennas work the same way, with the feed line pumping in energy at
just the "right time" to increase the current in the antenna?
The rig does not supply the electrons to the antenna (they were already
in those copper or aluminum atoms).
The rig supplies, via the feed line, the instructions as to WHEN to
push
those electrons.
Think of the feed line like GRAMPY pushing the GRANDKID.
We use the Nano VNA most likely in our (warm) shack. But perhaps we are
really interested in what the readings are at the ANTENNA junction.
By changing the feed line by a few feet (on 10 meters) I was able to
convince myself that adding about a 1/4 wavelength of RG213 (6 feet)
did
ROTATE the impedance values on the Smith Chart. I "knew" what was going
to
happen, but still smiled when I saw it with my own eyes. Yet, adding 6
feet of coax (to a 100 ft feed line) did absolutely nothing to the SWR
readings on 10m (28-29 MHz) to the REFLECTION COEFFICIENT, and to the
RETURN LOSS.
So I added these slides to my newest PDF file.
The attachment is my latest rendition of a NANO VNA talk (as pdf
slides).
If any clubs are looking for a speaker, I am all in. I learn a lot by
giving a talk on a topic (I'm at a 9th grader understanding of the VNA)
73 and TU for all of the helpful suggestions. Feel free to pass on
these
PDF slides to others.
de Barry Feierman k3eui
<Nano VNA Analyzer Jan 28.pdf>
--
*Dave - W?LEV*
*Just Let Darwin Work*
